package model;
import java.text.SimpleDateFormat;
import java.util.Date;
public class Person implements Cloneable{
private String name;
private int age;
private double salary;
private Date birthday;
public Person() {
}
public Person(String name, int age, double salary, Date birthday) {
this.name = name;
this.age = age;
this.salary = salary;
this.birthday = birthday;
}
public Person(String name, int age, double salary) {
this.name = name;
this.age = age;
this.salary = salary;
}
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public boolean equals(Object obj) {
if(obj instanceof Person){
Person comparePerson=(Person)obj;
return this.age==comparePerson.getAge();
}
return false;
}
@Override
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
@Override
public String toString() {
SimpleDateFormat format=new SimpleDateFormat("YYYY-MM-dd");
String finalBirthday="";
if(this.getBirthday()!=null){
finalBirthday=format.format(birthday);
}
return "Person [name=" + name + ", age=" + age + ", salary=" + salary + ", birthday="
+ finalBirthday + "]";
}
}
package stream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Map;
import java.util.OptionalDouble;
import java.util.Set;
import java.util.TreeSet;
import java.util.stream.Collectors;
import model.Person;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
public class StreamTest {
public static void init(List<Person> persons) {
Person person = new Person();
person.setAge(15);
person.setName("yy");
Person person1 = new Person();
person1.setAge(12);
person1.setName("lisi");
Person person2 = new Person();
person2.setAge(12);
person2.setName("zangwu");
persons.add(person);
persons.add(person1);
persons.add(person2);
}
public static void printPerson(List<Person> persons) {
persons.stream().forEach((o) -> System.out.println(o.getAge() + "--" + o.getName()));
}
public static void printPersonInfo(List<PersonInfo> persons) {
persons.stream().forEach((o) -> System.out.println(o.getAge() + "--" + o.getName()));
}
public static void main(String[] args) {
List<Person> persons = Lists.newArrayList();
init(persons);
printPerson(persons);
System.out.println("---------------");
List<Person> ageFilter = persons.stream().filter((o) -> o.getAge() > 11)
.collect(Collectors.toList());
printPerson(ageFilter);
System.out.println("---------------");
List<Person> sortPerson = persons.stream().sorted(sortByRule())
.collect(Collectors.toList());
printPerson(sortPerson);
System.out.println("---------------");
List<PersonInfo> personInfos = persons.stream().map(o -> convertToPersonInfo(o))
.collect(Collectors.toList());
printPersonInfo(personInfos);
System.out.println("---------------");
List<Person> limitPersons = persons.stream().filter((o) -> o.getAge() > 11).limit(1)
.collect(Collectors.toList());
printPerson(limitPersons);
System.out.println("---------------");
int ageCount = persons.stream().mapToInt(Person::getAge).sum();
System.out.println("所有人的年龄的和" + ageCount);
System.out.println("---------------");
//针对persons集合进行虚拟分页功能
int pageSize = 2;
int pageNum = 1;
int size = persons.size();
int from = (pageNum - 1) * pageSize;
int to = pageNum * pageSize;
if (size > from) {
List<Person> subListPerson = persons.subList(from, Math.min(to, size)).stream()
.collect(Collectors.toList());
printPerson(subListPerson);
}
System.out.println("---------------");
List<Person> skipPersons = persons.stream().skip(1).collect(Collectors.toList());
printPerson(skipPersons);
System.out.println("---------------");
OptionalDouble average = persons.stream().mapToInt(Person::getAge).distinct().average();
System.out.println(average.getAsDouble());
System.out.println("---------------");
List<Integer> aa = Lists.newArrayList();
aa.add(1);
aa.add(1);
aa.add(2);
aa.add(3);
aa.add(0);
int aaListSize = (int) aa.stream().distinct().count();
System.out.println(aaListSize);
System.out.println("---------------");
Map<String, Integer> personInfos1 = persons.stream().map(o -> convertToPersonInfo(o))
.collect(Collectors.toMap(PersonInfo::getName, PersonInfo::getAge));
System.out.println(personInfos1);
System.out.println("---------------");
List<Map<String, Integer>> personMap = persons.stream().map(o -> convertPersonTo(o))
.collect(Collectors.toList());
System.out.println(personMap);
System.out.println("---------------");
Person p = persons.stream().findFirst().get();
System.out.println(p);
System.out.println("---------------");
//集合最小
int min = (int) aa.stream().min((p1, p2) -> p1 - p2).get();
System.out.println(min);
System.out.println("---------------");
//集合最大
int max = (int) aa.stream().max((p1, p2) -> p1 - p2).get();
System.out.println(max);
System.out.println("---------------");
//集合最大
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
IntSummaryStatistics stats = numbers.stream().mapToInt((x) -> x).summaryStatistics();
System.out.println("List中最大的数字 : " + stats.getMax());
System.out.println("List中最小的数字 : " + stats.getMin());
System.out.println("所有数字的总和 : " + stats.getSum());
System.out.println("所有数字的平均值 : " + stats.getAverage());
System.out.println("---------------");
String nameList = persons.stream().map(Person::getName).collect(Collectors.joining(";"));
System.out.println(nameList);
System.out.println("---------------");
Set<Integer> ageSet = persons.stream().map(Person::getAge).collect(Collectors.toSet());
System.out.println(ageSet);
System.out.println("---------------");
TreeSet<Integer> ageTreeSet = persons.stream().map(Person::getAge)
.collect(Collectors.toCollection(TreeSet::new));
System.out.println(ageTreeSet);
System.out.println("---------------");
//聚合操作
Map<Integer, List<String>> res = persons.stream().collect(
Collectors.groupingBy(Person::getAge,
Collectors.mapping(Person::getName, Collectors.toList())));
System.out.println(res);
System.out.println("---------------");
Map<String, Double> res1 = persons.stream().collect(
Collectors.groupingBy(Person::getName, Collectors.averagingDouble(Person::getAge)));
System.out.println(res1);
System.out.println("---------------");
int sum = aa.stream().map((x) -> x).reduce(0, (x, y) -> x + y);
int sum1 = aa.stream().mapToInt((x) -> x).sum();
System.out.println(sum);
System.out.println(sum1);
System.out.println("---------------");
String[] strs = { "java8", "is", "easy", "to", "use" };
List<String[]> distinctStrs = Arrays.stream(strs).map(str -> str.split("")) // 映射成为Stream<String[]>
.distinct().collect(Collectors.toList());
distinctStrs.forEach(strings -> Arrays.stream(strings).forEach(s -> System.out.println(s)));
System.out.println("==================================map方式");
List<String> distinctStrsByFlatMap = Arrays.stream(strs).map(str -> str.split("")) // 映射成为Stream<String[]>
.flatMap(Arrays::stream) // 扁平化为Stream<String>
.distinct().collect(Collectors.toList());
distinctStrsByFlatMap.forEach(s -> System.out.println(s));
System.out.println("==================================flatMap的方式");
List<List<String>> testFlatMap = new ArrayList<List<String>>();
List<String> aaa = new ArrayList<String>();
aaa.add("a");
aaa.add("a");
aaa.add("c");
aaa.add("b");
List<String> aaa1 = new ArrayList<String>();
aaa1.add("ab");
aaa1.add("ab");
aaa1.add("cc");
aaa1.add("bd");
testFlatMap.add(aaa);
testFlatMap.add(aaa1);
System.out.println(testFlatMap.stream().flatMap(List::stream)
.collect(Collectors.joining(";")));
System.out.println("---------------");
Set<String> flatMap=testFlatMap.stream().flatMap(List::stream).collect(Collectors.toSet());
System.out.println(flatMap);
System.out.println("---------------");
}
private static Map<String, Integer> convertPersonTo(Person person) {
Map<String, Integer> personMap = Maps.newHashMap();
personMap.putIfAbsent(person.getName(), person.getAge());
return personMap;
}
private static PersonInfo convertToPersonInfo(Person person) {
PersonInfo personInfo = new PersonInfo();
personInfo.setAge(person.getAge());
personInfo.setName(person.getName());
return personInfo;
}
private static Comparator<Person> sortByRule() {
Comparator<Person> age = ((o1, o2) -> {
return Integer.compare(o2.getAge(), o1.getAge());
});
Comparator<Person> name = ((o1, o2) -> {
return o1.getName().compareTo(o2.getName());
});
return age.thenComparing(name.reversed());
}
private static class PersonInfo {
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
}
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